THE MICROTOMIST'S VADE-MECUM

Ill.
silver in a few seconds; chloral and glycerin are added as
before " (see ante, Hoyer's formula for carmine-gelatin, No.    T
393).
This mass is yellow in the capillaries and brown in the
larger vessels. It does not change either in alcohol, chromic
or acetic acid, or bichromate of potash, &c.
407. Gelatin Injection-mass (Green) (Hoyer's formula I).-
"Blue and yellow masses mixed give a very useful green."
408. Gelatin Injection-mass (White) (Carbonate of Lead)      lis
(Hartig's formula 2).- Dissolve 125 grammes of acetate of lead
in so much water that the whole shall weigh 500 grammes.        f
Dissolve 95 grammes of carbonate of soda in so much water
that the whole shall weigh 500 grammes.
Take equal volumes of the two solutions, and add two
volumes of gelatin-solution.
409. Gelatin Injection-mass (White) (Sulphate of Baryta)
(Frey's formula 3).-Put into a tall glass cylinder 125 to 185  O#
grammes of cold saturated solution of chlorate of baryta.      hour
Add drop by drop, very carefully, sulphuric acid. Allow the     shall
precipitate that forms to settle for twelve hours, then decant
almost all the clear supernatant liquid. The remaining muci-
laginous mass containing the precipitate is to be mixed with
an equal part of concentrated gelatin-solution.                thee
Frey states that this is a very finely-grained mass. Injected  rial
organs may be preserved in chromic acid.                        ttil
410. Gelatin Injection-mass (White) (Chloride of Silver)      For
(Teichmann's formula 4).-" Take 3 parts of nitrate of silver    1
dissolved in the gelatin solution, and add 1 part of common
salt."
The mass is very fine-grained, and is not decomposed by       5
chromic acid; the disadvantage of it is that it blackens under
the influence of light and of sulphurous solutions.             an
1 L. c.
Frey, ' Le Microscope,' p. 190.
3 Ibid.            4 Ibid., p. 191.

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